HD mouse-model studies have shown that rearing mice in an enriched environment delays the onset of symptoms, raising the possibility that pre-symptomatic lifestyle may also affect age-at-onset in humans. Furthermore the age-at-onset of other neurodegenerative disorders such as Alzheimer and Parkinson diseases can be influenced by the type and level of activity regularly undertaken prior to the development of symptoms. A study conducted in Australia and New Zealand showed that avoiding a passive lifestyle may well delay the onset of symptoms of HD. Substantiating these findings may mean that at-risk individuals can be given lifestyle strategies, which if employed from an early age, may lead to symptoms developing several years later than would otherwise be the case.

Description

The Environmental Modifiers Working Group aims to find evidence for, and identify environmental factors affecting age-at-onset. This will be pursued through examination of activities (both leisure and non-leisure) undertaken on a regular basis during the pre-symptomatic phase of HD. Initially this will involve collection of retrospective data from symptomatic individuals (from a much larger cohort than was possible in the Australasian study), with a view to ultimately developing a more definitive prospective study that will monitor activity in pre-symptomatic or at-risk individuals.

Current projects

Retrospective study – Looking at the impact of pre-symptomatic lifestyle on the age at onset of HD, as a follow-up to a preliminary study conducted in Australasia. The project uses a once-only, 20 – 30 minute, semi-structured interview to gather data relating to pre-symptomatic lifestyle history. Study participants need to be age 18 years or older with a diagnosis of HD confirmed by a neurologist, a mutation of known CAG repeat length in the IT15 gene, and be adjudged by a neurologist, neuropsychiatrist or psychologist as being capable of responding to a questionnaire in a meaningful manner. They should preferably, (but not necessarily) be accompanied by a family member.

Development of a prospective study - The ultimate aim of our project is to provide those at risk of HD with early (perhaps childhood) lifestyle interventions as a means of potentially delaying the onset of disease. However, this will require a detailed prospective study to identify specific factors and to show that their modification is indeed effective in producing a change in the mean age at onset. Thus, the results of the retrospective study, together with those already obtained in the Australasian study, will be used to inform the development of a prospective study of environmental factors and their impact on age-at-onset.

Prospective study – This phase of the project is yet to be formulated, but will involve participants who are at risk, but remain without symptoms of disease. We anticipate monitoring a range of environmental factors and lifestyle activities for their effect on age-at-onset. It may also be feasible in the future to extend this type of study to investigate the possibility that environmental factors may affect the progression of disease once the symptoms are evident.

Membership

The EMWG is currently seeking people with an interest in pursuing either the immediate and/or longer-term aims of the group. For the immediate aims we seek assistance with the hands-on task of conducting the retrospective study in centres throughout the network. For the longer-term we also seek those with appropriate expertise and interest to assist in the development and/or implementation of a prospective study of a range of environmental factors including physical, intellectual and passive activities in relation to the onset of HD, and to become an integral part of this working group.

Lead Facilitators

Dr. Kaye Trembath

Clinical Research Coordinator, Lead Facilitator Working Group Environmental ModifiersRoyal Children's Hospital, Murdoch Childrens Research Institute